U.S. patent number 4,367,645 [Application Number 06/212,583] was granted by the patent office on 1983-01-11 for hot gas sampling.
This patent grant is currently assigned to Kinetics Technology International Corporation. Invention is credited to Gilbert F. Froment.
United States Patent |
4,367,645 |
Froment |
January 11, 1983 |
Hot gas sampling
Abstract
Apparatus and method are provided to achieve efficient on-line
sampling of hot effluent gases from high temperature reactors. A
heated transfer valve is movable between sampling and injection
positions to control carrier gas and sample gas flow to a
chromatograph.
Inventors: |
Froment; Gilbert F. (Deurle,
BE) |
Assignee: |
Kinetics Technology International
Corporation (Pasadena, CA)
|
Family
ID: |
22791637 |
Appl.
No.: |
06/212,583 |
Filed: |
December 3, 1980 |
Current U.S.
Class: |
73/23.38;
73/23.42; 73/863.72 |
Current CPC
Class: |
G01N
30/20 (20130101); G01N 2030/8886 (20130101) |
Current International
Class: |
G01N
30/00 (20060101); G01N 30/20 (20060101); G01N
30/88 (20060101); G01N 031/08 (); G01N
001/22 () |
Field of
Search: |
;73/23.1,863.11,863.71,863.72,863.73 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Kreitman; Stephen A.
Attorney, Agent or Firm: Haefliger; William W.
Claims
I claim:
1. An apparatus for sampling a stream of hot gas containing
hydrocarbons, and employing a heated transfer valve, a source of
carrier gas for sampling and diluting the hot gas and transferring
it over a hot capillary coated pre-separation column to analytical
equipment, a gas splitter and a gas receiver, the improvement
comprising
(a) said transfer valve being heated and having multiple inlet
ports and multiple outlet ports,
(b) there being a sample receiving duct in communication with said
valve,
(c) said valve having relatively movable members defining a
sampling position, and an injection position,
(d) said sampling position characterized in that one inlet port,
the sample receiving duct and one outlet port are connected in
series to pass said hot gas to said receiver, and other inlet and
outlet ports are connected in series to pass the carrier gas to the
analytical equipment through the splitter and a hot line which is a
pre-separation coated capillary column,
(e) said injection position characterized in that said one inlet
port and said one outlet port are connected in series to pass said
hot gas to the receiver, and said other inlet port, said sample
receiving duct and said other outlet port are connected in series
with said source of carrier gas to pass a sample of hot gas in said
duct to the analytical equipment through the splitter and a hot
line which is a pre-separation coated capillary column,
(f) a gas chromatograph connected in series with the splitter to
receive a portion of the hot gas sample from the splitter, and
(g) a side passage connected with the splitter to pass split
carrier gas toward a flow controller.
2. The apparatus of claim 1 including a gas chromatograph connected
in series with the splitter to receive a portion of the hot gas
sample from the splitter.
3. The apparatus of claim 1 including a heated chamber or box or
container means in which said valve and said splitter are
received.
4. The apparatus of claim 3 including means to maintain the
interior of said chamber or box or container means at about
300.degree. C.
5. The apparatus of claim 1 including a cyclone connected in series
with said one inlet port.
6. The apparatus of claim 1 including said hot gas to be sampled in
said duct, and consisting of hydrocarbons, H.sub.2 O, hydrogen or
other chemical compounds.
7. The apparatus of claim 1 wherein said transfer valve has two
additional ports connected with said duct, whereby the valve has
six ports, the valve also having three internal passages
respectively connected with pairs of said ports in each of said
sampling and injection positions.
8. An apparatus for sampling a stream of hot gas containing
hydrocarbons, and employing a heated transfer valve, a source of
carrier gas for sampling and diluting the hot gas and transferring
it over a hot capillary coated pre-separation column to analytical
equipment, a gas splitter and a gas receiver, the improvement
comprising
(a) said transfer valve being heated and having multiple inlet
ports and multiple outlet ports,
(b) there being a sample receiving duct in communication with said
valve,
(c) said valve having relatively movable members defining a
sampling position, and an injection position,
(d) said sampling position characterized in that one inlet port,
the sample receiving duct and one outlet port are connected in
series to pass said hot gas to said receiver, and other inlet and
outlet ports are connected in series to pass the carrier gas to the
analytical equipment through the splitter and a hot line which is a
pre-separation coated capillary column,
(e) said injection position characterized in that said one inlet
port and said one outlet port are connected in series to pass said
hot gas to the receiver, and said other inlet port, said sample
receiving duct and said other outlet port are connected in series
with said source of carrier gas to pass a sample of hot gas in said
duct to the analytical equipment through the splitter and a hot
line which is a pre-separation coated capillary column,
(f) a gas chromatograph connected in series with the splitter to
receive a portion of the hot gas sample from the splitter,
(g) and including a side passage connected with the splitter to
pass split carrier gas toward a flow controller after removal of
another portion of the sample by means of an active charcoal
filter.
9. The apparatus of claim 8 including said flow controller
associated with said gas chromatograph and which has a capillary
coated pre-separation column via which a small fraction of the
sample gas is delivered to the gas chromatograph at a predetermined
flow rate controlled by the controller.
10. An apparatus for sampling a stream of hot gas containing
hydrocarbons, and employing a heated transfer valve, a source of
carrier gas for sampling and diluting the hot gas and transferring
it over a hot capillary coated pre-separation column to analytical
equipment, a gas splitter and a gas receiver, the improvement
comprising
(a) said transfer valve being heated and having multiple inlet
ports and multiple outlet ports,
(b) there being a sample receiving duct in communication with said
valve,
(c) said valve having relatively movable members defining a
sampling position, and an injection position,
(d) said sampling position characterized in that one inlet port,
the sample receiving duct and one outlet port are connected in
series to pass said hot gas to said receiver, and other inlet and
outlet ports are connected in series to pass the carrier gas to the
analytical equipment through the splitter and a hot line which is a
pre-separation coated capillary column,
(e) said injection position characterized in that said one inlet
port and said one outlet port are connected in series to pass said
hot gas to the receiver, and said other inlet port, said sample
receiving duct and said other outlet port are connected in series
with said source of carrier gas to pass a sample of hot gas in said
duct to the analytical equipment through the splitter and a hot
line which is a pre-separation coated capillary column,
(f) a heated chamber or box or container means in which said valve
and said splitter are received, said receiver comprising a liquid
containing vessel into which the discharge from said one outlet
port is connected, said vessel located outside said heated chamber
or box or container means.
11. In a process for sampling a stream of hot gas containing
hydrocarbons having 1-20 carbon atoms, and employing a transfer
valve, that includes
(a) maintaining said valve at elevated temperature,
(b) passing a sample of the hot gas stream via the valve into a
sampling duct communicating with the valve,
(c) passing a carrier gas through a channel in the valve,
(d) switching the valve to cause the carrier gas to entrain the
sample in said duct,
(e) splitting the carrier gas and/or entrained sample into two
streams while both are maintained at elevated temperature, and
(f) passing one of the streams to an analytical equipment strongly
diluted by the carrier gas through a pre-separation capillary
coated gas chromatograph column kept at a temperature of at least
200.degree. C., and
(g) passing the effluent of said column into a gas chromatograph
for further separation and determination of the gas composition, by
itself or in connection with a mass spectrometer,
(g) and passing the other of said streams toward a flow
controller.
12. The method of claim 11 including passing the other of the split
streams to a control which controls the ratio of the two
streams.
13. The method of claim 11 including providing a heated chamber
containing said zone, and carrying out said splitting in said
chamber.
Description
BACKGROUND OF THE INVENTION
This invention relates generally to on-line sampling of hot
effluent gases from high temperature reactors; more specifically,
it concerns apparatus and method to achieve efficient on-line
sampling of such gases.
There is a continuing need for efficient sampling of hydrocarbons,
some of which boil at high temperatures so that they condense in
the usual sampling devices which are at lower temperatures. Example
of such gases are those produced in the thermal cracking for olefin
production of hydrocarbon mixtures such as naptha, gasoil, etc. In
such processes, the effluent exits from the cracking coil at around
850.degree. C., and typically proceeds to a transfer line heat
exchanger with an outlet temperature of about 340.degree. C. The
effluent contains steam, hydrogen and hydrocarbons from methane up
to components having as many as 20 carbon atoms. It is of
importance to sample and analyse such an effluent at frequent
intervals under on-line conditions, to obtain up-to-date
information as to composition, rather than obtaining its
composition from periodic plant balances.
Prior attempts to achieve analysis of such gases include provision
of a device that had to be carried to a remote analytical
laboratory after receiving a hot gas sample. This and other devices
were plagued by condensation of heavy products, causing unwanted
fouling or plugging, and frequently leading to incorrect analysis
of the effluent.
SUMMARY OF THE INVENTION
It is a major object of the invention to provide a system and valve
device overcoming the above as well as other problems associated
with prior sampling methods.
Basically, the invention contemplates the obtaining of complete and
correct analysis of the hot effluent hydrocarbon gases, avoiding
plugging and fouling problems through the provision of apparatus
and method employing sampling of small quantities of effluent in
apparatus maintained at elevated temperatures, together with high
dilution of the sample with carrier gas and pre-separation by means
of a coated capillary line leading to a gas chromatograph.
In its apparatus aspects the invention basically employs a transfer
valve kept at high temperature and connected to a source of carrier
gas and to a gas chromatograph or other analytical equipment over a
capillary coated gas chromatograph column of 50 m or more. It is
characterized by:
(a) the transfer valve being heated and having multiple inlet ports
and multiple outlet ports,
(b) there being a sample receiving duct in communication with the
valve,
(c) the valve having relatively moveable members defining a
"sampling" position, and an "injection" position,
(d) the "sampling" position characterized in that one inlet port,
the sample receiving duct and one outlet port are connected in
series to pass the hot gas to a vessel in which bubbling indicates
flow through the duct and other inlet and outlet ports are
connected in series to pass the carrier gas to the splitter and the
analytical equipment and
(e) the "injection" position characterized in that said one inlet
port and said one outlet port are connected in series to pass the
hot gas to the bubbling vessel and said other inlet port, said
sample receiving duct and the other outlet port being connected in
series with the source of carrier gas to pass a sample of hot gas
in the duct to the splitter and the analytical equipment.
As will be seen, a gas chromatograph is connected over a coated
capillary gas chromatographic pre-separation column to the splitter
to receive a portion of the hot gas from a splitter; the gas
chromatograph itself also contains a separation column, of course;
the transfer valve and splitter are typically contained in a
chamber maintained at elevated temperature; and the transfer valve
has six ports, and multiple internal passages respectively
connecting pairs of said ports, as will be seen.
For its method aspects, the invention contemplates the steps:
(a) maintaining the valve at elevated temperature,
(b) passing a sample of the hot gas stream via the valve into a
sampling duct connecting with the valve,
(c) passing a carrier gas through a channel in the valve,
(d) switching the valve to cause the carrier gas to entrain the
sample in said duct,
(e) splitting the carrier gas and entrained sample into two streams
while both are maintained at elevated temperature, and
(f) passing one of the streams to a gas chromatograph through a
line which is a coated capillary pre-separation gas chromatograph
column kept at 200.degree. C.
These and other objects and advantages of the invention, as well as
the details of an illustrative embodiment, will be more fully
understood from the following description and drawings, in
which:
DRAWING DESCRIPTION
FIG. 1 is a system diagram;
FIG. 2 is a detailed frontal view of one form of valve as usable in
the FIG. 1 system;
FIG. 3 is a partially cut away side view of the FIG. 2 valve;
FIG. 4 is a frontal view of a relatively rotatable member of the
valve depicted in FIGS. 2 and 3, and in "sampling" position;
FIG. 5 is a view like FIG. 4 showing the member in relatively
rotated "injection" position;
FIG. 6a is a system diagram showing the valve of FIGS. 2 and 5 in
frontal view and in "sampling" position; and
FIG. 6b is a system diagram like FIG. 6a, showing the valve in
"injection" position.
DETAILED DESCRIPTION
In FIG. 1, a chamber or box 10 is suitably heated as by an
electrical heating element 19, as for example a Cal rod. The box
interior 10a is typically maintained at about 300.degree. C. Hot
gas effluent from sampling line 26 passes via line 26a to a small
cyclone 13 via inlet valve 12, the latter elements being in the
container heated interior 10a. An outlet valve for tar and coke
from the cyclone, is shown at 12a.
Gas to be sampled passes from the cyclone and through a filter 14
(as for example a gauze filter) that removes very small remanent
particulate. From that filter the gas to be sampled (i.e. gas such
as steam, hydrogen and hydrocarbons having from 1 to 20 carbon
atoms) enters a transfer valve 15, which is also heated by virtue
of its location within the heated interior 10a of the chamber
10.
Valve 15, which may take various forms, is characterized as having
multiple inlet ports (as for example at A and D as shown in FIGS.
2, 6a and 6b) and multiple outlet ports (as for example at B and E
as shown in FIGS. 2, 6a and 6b). Such ports are typically located
in a valve member 40 which is relatively non-rotatable. That member
also has ports as at C and F that are in communication with a
sample receiving duct 16 external to the valve (but within chamber
heated interior 10a) and of predetermined length corresponding to
the volume of sample gas to be analysed. Accordingly, the valve 15
is characterized as having six ports, identified at A-F.
FIGS. 3-5 also shows a relatively rotatable valve member 41, with
means 42 for rotating same about central axis 43, so as to provide
a "sampling" position of the valve as well as an "injection"
position. Such rotation is through a 60.degree. angle, allowing
very quick adjustment rotation of the valve. Member 41 has a face
41a slidably engaging face 40a of member 40, the drawings showing
that ports A-F pass through member 40 and intersect the interfaces
40a and 41a. Further, member 41 contains three transfer passages
44-46 spaced about axis 43 and of lengths to communicate between
pairs of the ports A-F in each of the "sample" and "inject"
positions referred to.
Referring to FIGS. 1, 6a and 6b, a source of "carrier" gas is shown
at 46a, and is connected via line 21 with port A. A typical carrier
gas is nitrogen.
.Port E is connected via line 47 with a receiver vessel 20
containing liquid, such as water, whereby gas leaving port E is
detected by bubbling of liquid in vessel 20. The latter is shown as
outside chamber 10. Port B is connected via line 48 with a
"splitter" 17 having inlet 17a and outlets 17b and 17c. Splitter 17
is located in chamber 10, and functions to remove a portion of the
gas to be sampled, for delivery at 17c along with carrier gas to a
capillary coated gas chromatograph column 23. The latter is
associated with gas chromatograph apparatus 24, having an
associated flow control 25. The latter may take the form of a valve
to pass the side gas stream delivered at 17b and passing through
"active" charcoal filter 22, wherein sample gas is adsorbed and
carrier gas flows through 49 to the controller 25. The adjustment
of the latter is such as to achieve a constant gas split ratio, as
between gas delivered at ports 17b and 17c.
The column 23 pre-separates the sample into its components prior to
injection into the gas chromatograph 24, also containing an
appropriate capillary coated column.
In operation, the valve 15 is first adjusted as by rotation of
member 41 to FIG. 5 position (see also FIG. 6b), for flushing of
the duct 16. Valve 12 is then opened. Effluent gas then flows via
line 26a, cyclone 13, filter 14 and via ports D and E and transfer
passage 45 to vessel 20. Carrier gas flows via port A, transfer
passage 44, port F, duct 16, port C, transfer passage 46, port B
and line 48 to splitter 17 and column 23 and line 49.
Subsequently, the six-way valve 15 is switched or adjusted into
sampling position (see FIGS. 4 and 6a) for a predetermined short
interval, such as about 5 seconds (for best results). In that
position, the furnace effluent flows via valve 12, cyclone 13 and
filter 14 to port D. From the latter, the effluent gas to be
sampled passes via transfer passage 46, port C, through the sample
loop or duct 16, port F, transfer passage 45, port E and line 47 to
bubble vessel 20. Bubbling at the end of the interval indicates
that duct 16 contains a predetermined volume of sample gas, without
carrier gas being present. Meanwhile, carrier gas flows via port A,
transfer passage 44, port B and line 48 to splitter 17. From the
latter, carrier gas flows via column 23 into chromatograph 24.
After the predetermined interval, the valve 15 is switched or
adjusted to FIG. 6b position (see also FIG. 5), for the injection
stage which lasts for another predetermined interval (about 10
seconds, for best results). In that position, the carrier gas
enters the valve via port A, travels via transfer passage 44 to
port F and enters duct 16 to drive the sample in the latter out
through port C, passage 46 and port B. From the latter, the sample
is driven to the splitter 17, through column 23 and to
chromatograph 24. Typically, only about one percent of the gas
contained in the sample duct 16 flows in this manner, ninety-nine
percent being diverted by the splitter through outlet 17b, filter
14 and to controller 25, which enables constant flow rates to be
established in both lines 23 and 49 leaving the splitter. Effluent
gas at this time passes via D, 45, E and 47 to receiver 20. After
the injection stage, the valve 12 is closed.
Examples of elements 15, 23, 24 and 25 are as follows:
______________________________________ Element Manufacturer Model
______________________________________ 15 VALCO Instruments
CV-6-HTa Houston, Texas 23 Supelco Inc. OV 101 Bell Fontaine, Pa.
24 Packard Instrument Co. 428 Burlingame, California 25 Packard
Instrument Co. 511 Burlingame, California
______________________________________
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